The conventional treatment of skin disorders such as ichthyotic dermatoses, hyperkeratosis and related conditions has included topical application to the affected area of skin of ointments, creams, lotions or powders containing one or more of a wide variety of active ingredients such as organic and inorganic acids, steroids, fungicides, antibiotics and anti-inflammatory substances.
Usually, remission of the disorder is slow and frequently incomplete. Complete remission and cure of some skin conditions can usually only be obtained by the use of potent drugs, such as steroids, having often severe contra indications which limit their widespread use without medical supervision. Also, the topical application of caustic chemicals in the treatment of localised conditions, such as warts, is often accompanied by pain or discomfort which also limits their use.
It has been suggested in the clinical literature that certain skin disorders are due to insufficient acidity in the epidermal acid layer or coat of the skin. Accordingly, certain skin conditions including one reported case of ichthyosis were apparently successfully treated by lowering the pH of the patient's acid coat. The treatment included topical application of a 3% buffered lactic acid-containing cream.
The use of 2-hydroxyoctanoic acid and 2-ketooctanoic acid in the treatment of acne has been reported in U.S. Pat. No. 4,507,319 (Lever Brothers Company). The benefit of treating other skin disorders, such as those referred to hereinbefore, is not contemplated in this reference.
It has also been reported in U.S. Pat. Nos. 3,879,537 3,920,835, 3,984,566, 3,988,470, 4,021,572, 4,105,782, 4,105,783, 4,197,316, 4,234,599 and 4,363,815 (Van Scott and Yu) that a wide variety of skin disorders may be treated successfully by applying topically to the affected skin at least one of several organic acids or esters thereof having from 2 to 6 carbon atoms and having .alpha. or .beta.-carbon functionality. These compounds are reported to include .alpha.-hydroxy substituted acids and keto acids having .alpha.-carbon functionality, and their esters. These and other specific acids and/or esters tested by Van Scott and Yu include glycolic acid, citric acid, lactic acid, maleic acid, tartronic acid, tartaric acid, glucuronic acid, pyruvic acid, (including its ethyl and methyl esters), 2-hydroxy isobutyric acid and 3-hydroxy butyric acid.
Extensive testing of these proposals has revealed that although some relief from at least some of the skin disorders reported in the Van Scott and Yu patents has been possible following treatment, complete remission of these disorders has not always been possible, nor is there any evidence that long term freedom from the symptoms of these skin disorders has been experienced when employing the compounds which are the subject of these prior proposals.
It has now been discovered that certain skin disorders may be treated successfully by topical application of a curative agent chosen from the organic acids, 2-hydroxyoctanoic acid, 2-ketooctanoic acid, and certain esters thereof. Comparative testing has shown that not only do these curative agents more rapidly bring about the remission of a wide range of skin disorders than does any of the compounds recommended for this treatment in the prior proposals summarised above, but that this effect is achieved at lower concentrations than the acids and esters specified by Van Scott and Yu. Furthermore, the effective remission of these disorders is far more long lasting. It is also evident that topical application of these curative agents is painless and free from contra indications, provided that the amount employed and their pH of use are kept within defined limits.
It is to be noted that 2-hydroxyoctanoic acid, also known as .alpha.-hydroxy caprylic acid, 2-ketooctanoic acid and their esters have not been contemplated by Van Scott and Yu as can be seen from a careful study of their patents. It is accordingly all the more surprising that these curative agents should have such a wide spectrum of activity in the successful treatment of skin disorders, the response to treatment following their topical application being far more rapid and dramatic than that of the related .alpha.-hydroxy organic acids and esters having up to 6 carbon atoms contemplated by Van Scott and Yu.